Electrical discharge device



Sept. 3, 1940. E. GERMER 2,213,245

ELECTRICAL DIS CHARGE DEVICE Filed Dec. 24, 1956 Patented Sept. 3, 1940UNITED STATES PATENT OFFICE Application December 24, 1936, Serial No.119,405 In Germany December 23, 1935 6 Claims.

This invention relates to illuminating devices and particularly to suchdevices of the gaseous discharge type.

' One object of my invention is to improve the efficiency of suchdevices. Another object of my invention is to provide illuminatingdevices adapted to give illumination of more satisfactory color value.Another object of my invention is to improve the length of the usefullife of illuminating devices. Another object of my invention is toprovide for the combining of such illuminating devices with pleasingvisual effects. Another object of my invention is to improve theuniformity of illumination produced by such devices.

Other objects and advantages of the invention will be apparent to thoseskilled in the art from the following description and the accompanyingdrawings.

In the drawings:

Fig. 1 is a view in axial section of a lamp embodying my invention. Fig.2 is a. view in side elevation of an arc tube designed for horizontalburning Fig. 3 is a view in cross-section showing another embodiment ofmy invention designed particularly for use in connection withfluorescent materials.

Fig. 4 is a cross-sectional view similar to Fig. 3,

6 but including both lamp and jacket and illustrating an embodiment ofthe invention in which the fluorescent material is carried by thejacket. I Fig. 5 is a view partly in axial section and partly inelevation of a so-called super high pressure type lamp embodying myinvention.

Fig. 6 is a view in elevation partly broken away of a lamp and reflectorcombination.

Referring first to Fig. 1, I have there shown for example a gaseousdischarge lamp adapted Y particularly for operation at high temperatures9 ,with a metal vapor atmosphere in which the discharge occurs. This maybe, for example, a high pressure metal vapor discharge tube of the typedescribed and claimed in my prior coper'ding application, Serial No.500,346, filed Dccember 5, 1930. The lamp consists broadly of an innersealed envelope to having in-lead wires ll sealed through opposite endsthereof as indicated at 12 and supporting thereon activated self-heatingelectrodes l5. These electrodes may consist, for example as shown, of acylindrical roll, advantageously several layers thick,

. of nickel wire mesh, into the interstices of which is worked theactivation material, e. g., as set forth in my said prior application.

- This inner envelope I0 is supported within a sealed jacket 15 to theend of which is advantageously secured a suitable connector base, e. g.,of the Edison Mogul type.

Supporting the inner envelope l0 within the 5 jacket I5 is a spring ringI6 at each end of the envelope It). This ring may consist of a coiledwire spring or it may be a thin annular tube or other member, butpreferably has some resilient compressibility towards the center of the10 tube or the spiral l6 as well as towards and. away from center of thering.

The end of the tube ID as shown in the drawings is provided with aconstriction IT in which the metal ring l6 rests; and due to theconfining action of the jacket l5, once the ring and tube ID areinserted therein, the ring I6 is locked in the constriction I! and thereis no danger of its becoming separated from the tube l0.

Advantageously a strip of mica or other intercepting material 18 isinserted between the tube In and the ring 16. If desired also, andespecially if the mica strip I8 is used, the rings H5 or either of themmay be connected to the opposite electrode so as to serve as anauxiliary capacity electrode for starting of the discharge.

The space between the jacket l5 and the inner envelope I0 may beevacuated or filled with a suitable gas.

The wall of the tube Illa according to my invention is increased insurface area, e. g., by corrugating as shown in Fig. 2. Thus a greatersurface for radiation and transmission of radiation from the vicinity ofthe arc path can occur.

An important advantage bf this increased surface area e. g. as shown inFig. 2 comes into existence when luminescent, e. g., fluorescent orphosphorescent, materials are used with the tube, either applied to itssurface, inside or outside, or in the material of the glass itself. Itis often a disadvantage of such materials either that they are more orless opaque, in which case they tend to intercept light passing throughthe tube and thereby reduce the efliciency of the tube even as it isincreased by the conversion of ultra-visible radiation into visiblelight, or that the fluorescent materials are deteriorated by intenseradiation. In either case the extension of the surface, e. g., bycorrugation, etc, is an advantage. In the one case itpermits, with thesame amount of fluorescent material, a lesser density in the glass orthe coating and thereby a lesser loss of light by absorption. In theother case it permits, by

the extension of the surface, a less intense radiation of thefluorescent materials per unit area, so that their life may thereby beincreased.

A similar effect can also be obtained by lesser irregularities in thesurface, e. g., by severe etching or frosting of the glass, by grooving,waffling, etc., or by other types of corrugation. These I haveillustrated particularly in Figs. 3, 4 and 5.

In Fig. 3, I have shown in cross-section the inner envelope 10b made instar shape. In Fig. 4, the inner envelope I is of the usual circularshape whereas the outer jacket I51) is made star shap d. In Fig. 3, ofcourse, the fluorescent material will be applied to the inner envelope,whereas in Fig. 4 it will be applied to the jacket, preferably theinside of the jacket. The luminescent material may also be dividedbetween the jacket and the inner envelope, which again increases thesurface on which the material is exposed to radiation. In this case bothmay for example be star shaped. With this double arrangement a materialadapted to convert ultraviolet radiation into visible light may be usedon the envelope and one for converting the blue and violet into longerwave length light may be used on the jacket.

The envelope and/or the jacket themselves may in any case be of clear orcloudy glass, silica or other suitable light permeable material and thefluorescent material may be applied to either the inner or outer surfaceor incorporated within the glass.

In Fig. 5, is shown an example using a super high pressure lamp in aglobular jacket. These super high pressure lamps are ordinarily made ofsmall bore quartz tubing, having electrodes sealed into opposite endsand a small drop of mercury. The lamp itself may vary from about oneinch to several inches in length and may operate with a mercury vaporpressure of many atmospheres. The electrodes are of the solid activatedtype heated by the action of the discharge itself. In the exampleillustrated in Fig. 5, this inner envelope Illc is supported from thestem seal 20 by the wires 2!, 22, one of which serves as the return leadfor the current from the farther electrode. The cross wires 23 hold theenvelope lllc between the wires 2| and 22. The outer jacket 150, asshown in this figure, is made of pressed glass with the inner surfacewafiled or cross-grooved to form upstanding diamond shaped projections,thus increasing the surface area on which suitable fluorescent materialmay be carried, e. g., by coating, enamelling or reglazing, etc., or thesurface-increasing projections on the interior of the tube may be formedby deep etching of the surface of the glass after it is blown or molded.

The globe I50 is secured, e. g., in the usual manner to a connector base24 of any suitable design, and may be sealed, e. g., by fusing to thestem press 20 or may be cemented thereto or mechanically secured with acushioning washer, e. g., of asbestos, between.

Instead of forming the surface-increasing projections only on the insideof the tube, e. g., by molding, the entire wall of the tube may beformed into surface-increasing projections, grooves, corrugations, orother irregularities, e. g., by blowing a thin walled globe into a moldof suitable shape.

Since the ultra-violet light passes readily through the quartz wall ofthe super high pressure lamp the fluorescent material is preferablycontained on the inner increased area surface of the pear-shaped globeand the space between advantageously is evacuated or filled only withgases which are readily permeable to ultraviolet radiation. Thus theultra-violet radiation substantially undiminished is converted intovisible light which passes easily through the wall of the jacket 150.The efilciency of such an arrangement is as great as when fluorescentmaterials are used inside the inner envelope, but it is far morepracticable because on the jacket they they are not subjected toexcessively high temperatures, to ionic and electronic bombardment orelectrolysis (conditions which may exist on the inner envelope), and itis not necessary to subject them to severe degassing treatment andfinally because of the greater surface area the radiation to which theyare subjected is less severe.

If, however, the increased surface and the coating of fluorescentmaterial .were on the outside of the jacket lc, the ultra-violetradiation would be absorbed to a greater or lesser extent by anyordinary glass in the wall of the jacket. If such an arrangement isadopted, therefore, the glass of the jacket I50 would preferably be anultra-violet permeable material. In general, however, it is better toutilize the inner surface for this purpose, and in such case the jacket150 may be made of any light-permeable glass capable of withstanding thetemperature conditions to which it is subjected in operation.

It should not be understood, however, that the exterior surface of thejacket could not be used, even if it is made of a material substantiallyimpermeable to ultra-violet radiation. Even in such case, it may bedesirable to give a better balanced radiation by converting a part ofthe short wavelength blue and violet light into a longer Wavelengthradiation within the visible spectrum. Obviously, also the light sourcelOc used in this case may be a larger ordinary high pressure vapor lampor a low pressure hot or cold cathode discharge lamp, including theso-called cathode glow discharge lamp.

Where a balanced white light is desired, 1 have found that aparticularly desirable effect can be obtained by combining the spectrumof mercury and the spectrum of sodium with fluoresccnce produced by arhodamin fluorescent layer. For this purpose, an arrangement similar tothat shown in Fig. 7 may be used, with the rhodamin contained on theinner surface of the globe c and the filling within the envelope lllcconsisting of carefully regulated amounts of mercury and sodium andadapted to produce joint emission, e. g., as set forth in the copendingapplications of Hans J. Spanner, Serial No. 558,148, filed August 19,1931, Serial No. 643,502, filed November 19, 1932, Serial No. 714,949,filed March 10, 1934, Serial No. 190,642, filed February 15 1938.

Rhodamin has been combinedbcfore with mercury light to add its redradiation to the bluegreen light of the mercury spectrum. Suchcombination, however, still fails of perfect balance because of a lackin the orange-yellow range in the spectrum, which according to myinvention is provided by the sodium spectrum. This combination of themercury spectrum, the sodium spectrum and the rhodamin fluorescencespectrum gives a particularly well balanced light and a much higherefiiciency than the combination of the mercury lamp with an incandescentlamp.

In Fig. 8, I have shown another way of achieving a similar result. Inthis case a mercury spectrum and the sodium spectrum are provided byseparate lamps 26 and 21 within a common reflector 28. This reflector 28may serve as the heat confining jacket for the lamps 26 and 21,protecting them from draughts and excessive convection currents. In somecases it will be preferable to provide a closed end of glass or othertransparent material at the bottom 29, in many cases the bell shapedreflector will so far trap the hot gases which tend to rise from thelamps as to be adequate without a bottom.

The reflecting surface 28 may also be corrugated, waflled or otherwiseprovided with an increased surface area, as already described above, toreduce the intensity of the radiation per unit of surface on thefluorescent material. Other fluorescent materials than rhodamin, andother types of lamps using other spectrum producing gases or vapors canbe similarly combined and advantage taken of the increased area of thereflector as described.

Obviously, instead of a metal vapor filling using a permanent gas onlyfor starting, the tubes may also be filled with permanent gases like, e.g., neon-helium and the spectra of the gases utilized for lightproduction.

What I claim is:

1. In an illuminating device the combination of a light source adaptedto give ultra-violet radiation and a wall exposed to radiation from thelight source having a surface provided with projections, depressions andthe like, whereby to increase its surface area, and a luminescentmaterial on said surface of increased area exposed to radiation from thelight source.

2. An illuminating device as defined in claim 1, in which the wallhaving the surface of increased area and carrying the luminescentmaterial is a jacket enclosing the light source and made of a materialpermeable to light but relatively impermeable to ultra-violet radiationand the surface of increased area which carries the fluorescent materialis the inner surface exposed to the ultra-violet radiation of the lightsource.

3. In an illuminating device the combination,

of gas discharge means adapted to excite to luminous radiation mercuryvapor and sodium vapor and a wall exposed to radiation from both vaporsof said discharge means and carrying thereon rhodamin.

4. In an illuminating device the combination of a. light source adaptedto give both visible and ultra-violet radiation, and a wall exposed tosaid radiation, the wall having faces which are angularly related to thelight source and to one another, and having luminescent material at saidfaces to convert ultra-violet to visible light, said luminescentmaterial being on the side of said faces exposed to the light source,whereby to have a large surface of luminescent material exposed to thelight and to cause light reflected by the luminescent material to beincident upon a neighboring part of the wall.

5. In a luminescent lamp the combination of a light source and a carrierbody having a surface thereof uneven so as toincrease the surface areawhich is exposed to the light source and a luminescent substancedistributed thereon and held thereby.

6. In a luminescent lamp the combination of a light source, an envelopetherefor at least a part of which has a surface area substantiallygreater than is required by its major dimensions and a luminescentmaterial distributed on said part and exposed to radiation from thelight source and visibly to the exterior of the lamp.

EDMUND GERBER.

